“Double-flash” copper-refining technique is: copper concentrate→flash melting→matte→flash converting→coarse copper→positive-pole refinement→anode copper→electrolysis→high-purity cathode copper. As the most advanced technique in copper refinement at present, it represents the development direction in the future, but sulfur content in the coarse copper produced in flash converting process is higher than that in traditional PS furnace converting, to see sulfur content in flash converting 0.1-5%, while that in PS furnace converting 0.03-0.08%. Now, traditional method of deep oxidization and reduction is still adopted for the fire-refining of these high-sulfur content coarse copper, i.e. air or oxygen is first led in to carry out deep oxidization to reduce sulfur content in copper liquid to less than 0.003%, then use reducers, such as natural gas, liquefied petroleum, heavy oil, diesel oil or pulverized coal to conduct deep reduction to eliminate surplus oxygen. This method, featured with first deep oxidization and then deep reduction, will not only consume large amounts of natural gas and other nonrenewable resources, wasting energy sources, but also prolong refining time, reduce refining efficiency, and the working condition is bad, environment pollution severe.